In the ordinary internal combustion engine and in some steam engines, the alternating rectilinear movement of the pistons is transformed into rotary motion by means of connecting rods connected to a crankshaft.
This arrangement is somewhat inefficient because the angle between the connecting rod and the crank of the crankshaft is generally far from 90.degree. at the moment of cylinder detonation. In fact, the connecting rod and the crankshaft may almost be in alignment at that time. Consequently, the torque that the piston is able to exert on the crank of the crankshaft at the moment of detonation is minimal. Although this system is generally conservative, some energy loss occurs as a result of this near alignment of the connecting rod and crank, which results in some loss of efficiency.
For engines having the same cubic inches, a small diameter piston offers greater burning efficiency because the force of the exploding gasses is distributed more evenly over the surface of the piston. However, this improvement is off-set in the conventional engine by the long piston stroke required to obtain the same cubic inches. This long stroke requires a longer crank in the crankshaft, which is less efficient.
If the pistons had a larger diameter, the stroke of the pistons would be smaller, so that the crank of the crankshaft would be shorter and more efficient. However, this greater efficiency is offset by the fact that the exploding gasses in the cylinders at detonation would be distributed less evenly over the surface of the piston.
A rack and pinion connected between the pistons and the drive shaft, wherein the alternating movement of the pistons is transformed into a rotary movement by means of a mechanical rectifier permits the design of a long stroke engine with small area pistons and a reduced function crankshaft in order to improve the efficiency of the engine.
In the past, many efforts were made to design internal combustion engines with a rack and pinion arrangement for the transfer of power to the transmission, in place of the conventional connecting rod and crankshaft arrangement. But these prior efforts were not commercially successful in the era of low cost fuel, because the energy savings then were unimportant. Now, however, the increased cost of energy has generated renewed interest in the rack and pinion connected between the pistons and drive shaft because even a small increase in engine efficiency may be economically attractive.
Heretofore mechanisms for transforming alternating piston motion into a uni-directional rotary motions were expensive and complicated. For example, the patent to Stenz, U.S. Pat. No. 1,026,184, teaches the use of sectored gearing for the transmission of reciprocating movement and the avoidance of crankshafts with consequent dead points. (See column 1, lines 7-15 therein.)
The patent to Flood, U.S. Pat. No. 1,316,437, utilizes a rack and pinion in an arrangement which eliminates the need for a crankshaft, connecting rods and the like. In Flood, a spur gear engages the upper teeth of a sliding gear in one direction and the lower teeth of the sliding gear in the opposite direction to provide uni-directional rotary motion.
The patent to Powell, U.S. Pat. No. 1,545,516, is designed to prevent an engine from being at dead center at any time during the firing stroke. This is achieved through the use of a differential movement between the crank members and the crankshaft and the piston rod.
The patent to McClurkin, U.S. Pat. No. 1,827,248, discloses a piston with an internal rack and pinion arrangement attached thereto, arranged somewhat like the Flood patent, supra. The orbital movement of the rack permits the pinion to rotate in one direction.
The U.S. Pat. No. to Latil, 2,155,497, discloses a piston in an internal combustion engine, wherein a rack secured to a piston meshes with a sectored pinion which drives the main engine shaft. A connecting rod is secured at one end to the lower end of the rack and at the other end to the crank of a crankshaft. The crankshaft is driven by a system of gears at a speed twice that of the power output shaft to cause proper meshing of the sectored pinions with the upper tooth of the rack at the time of piston detonation.
The patent to Brezenski, U.S. Pat. No. 2,088,504, converts reciprocating movement to rotary movement by a programmed disengagement of the rack bar from the pinion on the piston up-stroke.
The U.S. Pat. No. to Dillenback, 2,239,663, utilizes ratchet gears which mesh with ratchet bars in one direction and which are disengaged from the ratchet gears in another direction to achieve rotary motion. (See FIG. 8.)
The patent to Julin, U.S. Pat. No. 2,337,330, teaches the use of racks and gears and segmental gear wheels which alternately engage the pinion as the pistons rise and fall. The segmental gears are connected to a common gear to provide uni-directional rotary motion.
The patent to Julin, U.S. Pat. No. 2,757,547, is somewhat similar to U.S. Pat. No. 2,337,330, and achieves rotary motion by disconnecting a driven shaft from the drive shaft through the use of segmental gears which alternately connect the driveshafts to the driven shafts.
All the above described patents disclose rather complex mechanisms and result in an engine which is large, heavy and expensive.
Applicant has achieved a useful decrease in engine complexity, size and weight, in an internal combustion engine having a rack and pinion arrangement by reducing the function of the crankshaft.
In this case, the power output function of the crankshaft is removed from the crankshaft, and the crankshaft which rotates at the same speed as the power output shaft is used to provide a flywheel function and to control the timing. In this way, power losses inherent in the long stroke piston movements is reduced because the crankshaft does not deliver power.
In addition, as will be seen, the present arrangement provides an automatic free-wheeling effect because if the engine drive shaft were rotating at a speed greater than the rotational speed of the mechanical rectifier, the mechanical rectifier and the pistons and piston rack will be disconnected from the engine drive shaft, even during the down or power stroke. With this arrangement, if the engine were installed in an automobile, moving at a high rate of speed, the engine would not be a drag on the velocity of the car if the driver of the car takes his foot off the gas. It would be as though at high rates of speed, the car is put in neutral. In contrast, at lower speeds, when the rotational speed of the power output shaft is less than the rotational speed of the mechanical rectifier, this effect would not occur. This results in a greater savings of energy at high engine speeds, and this effect is achieved without the use of additional parts, because it is inherent in this engine design.
Moreover, the rack and pinion arrangement also transmits torque to the pinion at 90.degree. during the entire piston stroke, which results in somewhat greater efficiency, thereby producing a smoother and more efficient running engine.
What is needed, therefore, and comprises an important objective of this invention is to provide a rack and pinion mechanism for engines of a kind where the pinion drives the power output shaft and which is simple to construct and which results in a more compact, lightweight engine.
A further objective of this invention is to provide an internal combustion engine or steam engine which utilizes a rack and pinion to drive a power output shaft and wherein the function of the crankshaft is reduced so that it only has to return the pistons to the proper position in the cylinders in position for the next power stroke.